/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 *
 * @format
 * @oncall react_native
 */

"use strict";

const { Logger } = require("metro-core");

/**
 * Main cache class. Receives an array of cache instances, and sequentially
 * traverses them to return a previously stored value. It also ensures setting
 * the value in all instances.
 *
 * All get/set operations are logged via Metro's logger.
 */
class Cache {
  constructor(stores) {
    this._hits = new WeakMap();
    this._stores = stores;
  }
  async get(key) {
    const stores = this._stores;
    const length = stores.length;
    for (let i = 0; i < length; i++) {
      const store = stores[i];
      const name = store.constructor.name + "::" + key.toString("hex");
      let value = null;
      const logStart = Logger.log(
        Logger.createActionStartEntry({
          action_name: "Cache get",
          log_entry_label: name,
        })
      );
      try {
        const valueOrPromise = store.get(key);

        // $FlowFixMe[method-unbinding] added when improving typing for this parameters
        if (valueOrPromise && typeof valueOrPromise.then === "function") {
          value = await valueOrPromise;
        } else {
          value = valueOrPromise;
        }
      } finally {
        Logger.log(Logger.createActionEndEntry(logStart));
        Logger.log(
          Logger.createEntry({
            action_name: "Cache " + (value == null ? "miss" : "hit"),
            log_entry_label: name,
          })
        );
        if (value != null) {
          this._hits.set(key, store);
          return value;
        }
      }
    }
    return null;
  }
  async set(key, value) {
    const stores = this._stores;
    const stop = this._hits.get(key);
    const length = stores.length;
    const promises = [];
    for (let i = 0; i < length && stores[i] !== stop; i++) {
      const store = stores[i];
      const name = store.constructor.name + "::" + key.toString("hex");
      Logger.log(
        Logger.createEntry({
          action_name: "Cache set",
          log_entry_label: name,
        })
      );
      promises.push(stores[i].set(key, value));
    }
    await Promise.all(promises);
  }

  // Returns true if the current configuration disables the cache, such that
  // writing to the cache is a no-op and reading from the cache will always
  // return null.
  get isDisabled() {
    return this._stores.length === 0;
  }
}
module.exports = Cache;
